Stocks in Europe rallied as investors welcomed declining yields on Spanish and Italian bonds. The yield on the 10-year Spanish bond briefly topped 6% before retreating to 5.88%; Italian 10-year yields fell to 5.51% from 5.69%.

"Europe has come back today, and we've followed it," said Ben Schwartz, chief market strategist at Lightspeed Financial. Despite the rebound, Schwartz said trading volumes were low and the market remains "vulnerable."

It's been a rough stretch lately for U.S. stocks, with the major indexes down more than 3% this month.

But stocks are still priced at attractive levels, and with yields on many U.S. Treasuries trading below inflation, investors have few other alternatives, said Tim Courtney, chief investment officer at Exencial Wealth Advisors.

"There's no good place to park the money that's exited the market over the last few days, so its coming back in," he said.

Meanwhile, investors will be looking for reason to reverse the recent losses as they shift their focus to the upcoming batch of corporate results.

Economy: Prior to the opening bell, the Bureau of Labor Statistics reported that U.S. import prices advanced 1.3% in March, while exports rose 0.8%.

The Federal Reserve released the April edition of its Beige Book, a summary of outlooks from the 12 district banks across the country. The Fed said economic activity continued to expand at a "modest to moderate pace" from mid-February through late March.

Companies: U.S.-listed shares of Nokia (NOK) fell 16% after the company lowered its first-quarter outlook. Nokia cited "competitive industry dynamics," the macroeconomic environment, and gross margin declines in its smart devices unit, in explaining the revision.